Extract Fitted Covariance Structures
getReCovs.RdReturns a list with one covariance object for each
random effect in the model. If the object is an old-style (pre-version
2.0.0) fitted model, it automatically converts all terms to
Covariance.us objects (except for terms including double-bar
‘||’ notation, which are converged to Covariance.diag
objects).